Method of drying and handling wood veneer



March 23 1926.

A. ELMENDORF METHOD 0F DRYNG AND vHANDLING WOOD VENEER Filed Newa 2.1.1921 MO/src/RE CONTE/v7' Patented Mar. 23, 1926. i

UNITED STATES A l 1,518,020 PATENT OFFICE.

ARMIN ELMENDORF, OF CHICAGO, ILLINOIS.

METHOD OF DRYING AND HANDLING WOOD VENEEB.

Application led November 21, 1921. SerialI No. 516,528.

To all whom it may concern.'

Be it known that I, ARMIN ELMENDORF, a citizen of the United States,residing at Chicago, county of Cook, State of Illinois, have invented acertain new and useful Improvement in Methods of Drying and HandlingWood Veneer, and declare the following to be a full, clear, and exactdescription of the same, such as will enable others skilled in the artto which it pertains to make and use the same, reference being had tothe accompanying.drawings, which form a part of this specification.

The common method of handling wood veneer 1s to cut or tear 1t lntosheets as 1t 1s formed from the log, the sheets being then dried andreaching the consumer in what should be a l'lat dry state. There 'areseveral' common methods of drying, namely between hot plates,betweenrolls in a heated chamber, and in kilns. It is very seldom that a sheetof veneer emerges from the drying rocess without beine` war ed andcracked.'

and transporting them, furtherbreaking or cracking thereof, particularlyalong the edges, invariably occurs. Therefore when the veneer reachesthe consumer who is to work it up into finished products, it is in theform of more or less warped and cracked sheets which must be flattenedand trimmed, the trimming alone often resulting in a great waste ofmaterial due to the fact that a large percentage of the stock mustsometimes be cut away to remove portions unfit for use.

The object of the present invention is to produce a simple, novel andeconomical method of handling and drying veneer, so that the veneer willreach the consumer in a sound unwarped condition and there will be aminimum waste of material from the time the veneer is fashioned from thelog to the time it is cut up by the consumer.`

When veneer is cut from the log it is in a wet state, that is a state inwhich the moisture content is above what is known as the libersaturation point. As long as the moisvture content remains abovethesaturation point there is substantially no expansion or contractionof the veneer as the amount of moisture increases or decreases. As soonas the moisture content drops below the saturation point, in the dryingof the veneer, contraction across the grain begins. Similarly for anyincrease or decrease in the moisture content, as long as the totalremains below the saturation point, there is a correspondlng expanslonor contraction of the veneer.

In the ordinary methods of handling veneer,

it is dried sufficiently, in the course of manufacture, to reducemoisture content below the saturation point, thus permitting crackingand warping to take place and leaving the sheets in a comparativelyfragile condition which causes them to break and crack still moreduring' subsequent transportation and handling.

In accordance with my invention the veneer is not out or broken intosheets as it is formed, but is rolled up so that if desired, Iall of theveneer obtained from a log may be in a single long sheet. I then drythesheet by carrying it through a suitable drying'chamber in which theheat, humidity.

and convection factors are properly coordinated effectually to dry theveneer, without` danger of checking the surface, until the moisturecontent has dropped toa point in the vicinity of the saturation point.This first drying step does not result in any apreciable contraction ofthe veneer but, a er the saturation point has'been passed in thedownward direction, further drying is accompanied by a contraction ofthe veneer. The second stage of the drying is accomplished While theveneer is being held together in such a manner that it cannot be splitalthough retaining its natural liexibility. The most. convenient Way tohold the veneer together and prevent it from splitting is to attachadhesive tapes to the same when, in its travel, it reaches a. pointwhere the moisture content is in the vicinity of the saturation point.The adhesive tape is preferably made of cloth or other strong flexiblematerial and, while the veneer is shrinking in thei direction of thelength of the tapes during the second stage of the drying process, thetapes do not shrink but compensate for the shortening-of the veneer byWrinkling. This Wrinkling of the'tapes o f course loosens them and, ifleft loose, would make them useless. I therefore press down the'wrinklesas they are formed so that the tapes are in effect progressivelyshortened by a wrlnkling operation and kept cemented to the veneernotwithstandingsuch wrin- 'kling. VThe tapes, even in their wrinkledconditions, therefore possess tensile strength in the direction `oftheir lengths and serve effectively to tie or bind the fibers togetherand prevent cracking or splitting. The drying operation is preferablycontinuous, the sheet of veneer being progressively unrolled, dried, andagain' rolledup with the tapes fastened thereto. During the dryingprocess the veneer is fed transversely to the grain and over guideswhose axes are parallel with the grain, the guides being preferably sodisposed that the veneer is bent first in one direction and then in theother to make a series of transverse corrugationse thereby insuring thatthe drying will be accomplished while a line drawn transversely of thesheet at any point remains a straight line which ultimately becomes anelement of a cylinder when the veneer is rolled up after the dryingoperation.

The'dried and taped roll-bf veneer may vbe transported and handled inthat form, no

division of the material into strips or panels being done until theveneer reaches the` user. When the veneer reaches the user it is Hatalong transverse lines and may read-y ily be iattened out in thelengthwise direction. Since there is no splitting or cracking of theveneer in drying, there will be little need for cutting away stock alongthe edges in order to remove unsoundfportions.

The various features of. novelty whereby my invention is characterizedwill herein` after be pointed out' with particularity in l lowing the2claimsybut, for a full understanding of my invention and'of itsobjectsy and.ad vantages reference may be had to the fol-` detaileddescription taken in' connection with the accompanying drawing, wherein:i Y

Figure'l. is a diagram showing va typical expansion and con-tractioncurve for wood based on .variation in Amoisture content;

Fig. 2 is a side elevation, with the nearl wall removed,'of an apparatusin which my vinvention may conveniently be carried out;

Fig. 3 is a section taken approximately Online d---l of Fig. 2; andVFig. 4 is a section taken approximately on line 4 4 of Fig. 2. y

A Referring to the drawing, A represents a Aroll of wet veneer which isadapted to be supported in suitable bearings l outside of and near thetop of a vertically-elongated chamber 2. In the chamber 2 are a seriesof light rollsv 3 of comparativelylarge diameter, the lowermost rollbeing at the bottom of the chamber and being supported so as to be heldagainst movements other than rotary movements. The lower roll may bedriven element co-operating with a gear wheel or,

sprocket wheel 4 mounted on the roll. The remaining rolls of the seriesrest one upon the other, their journals 5 projecting into slots or waysformed between pairs of vertical guides 6 arranged at opposite ends ofthe rolls. This arrangement permits the rolls to rotate freely incontact with each other and to adjust themselves in the vertical di-Arection. Behind the uppermost roll and every other roll of the seriesare arranged guide fingers 7 while in front of the remaining rolls ofthe series are similar guide fingers 8. The fingers are so proportionedthat when the sheet of veneer a is passed into the top of the chamber 2through a slot or opening 9, it will move across the top of theuppermost roll and then be` deflected downwardly around the roll andfforwardly across the top of the second roll where it engages with theguide fingers 8 in front of the sec- 0nd' roll and is carried downaround the front of the second roll and underneath the latter. In thisway when the veneer is fed into the apparatus, it will be positivelyguided in position between each pair of rolls and, by the time itreaches the bottom of the chamber, it has taken on a sinuous or deeply.

waved form.. However, the curvatures are all in one direction, all linesextending transversely of the sheet being kept straight. Furthermore, asany section of the sheet passes along the series of rolls it is firstbent in one direction and then in the opposite direction so that thereis no tendency to give it a permanent curvature.

When the lowermost roll of the series is driven, all of the other rollsare set in motion, each roll forming with the next one above it afriction drive. This relation between the rolls is not disturbed by thepresence of the veneer between them because each section of veneer'actsas thoughit were a part of the lowermost roll along the line of contactbetween two rolls. As the lowermost roll is driven, the entire seriesfissetin rotation andthe veneer lis advanced-downwardly ythrough thechamber.` Within the chamber are steam coils 10. At the top of thechamber is an outlet flue 11 controlled by a damper 12. Within thechamber are fans 13 at opposite ends of the rollers, although only onesuch fan is illustrated in Fig. 2. As the veneer passes down through thechamber, itis gradually dried, the vari-v ous factors entering into thedrying process `one end of the latter.

chamber the veneer moves free from tension because there is no shrinkingof the veneer on account of the loss of moisture until the vicinity ofthe saturation point has been reached. Therefore there is no dangerftearingl the veneer.

The upright chamber 2 communicates with the top of a horizontal chamber14 at In this horizontal chamber are a. series of rolls 15 spaced apartfrom each other and arranged in staggered 'relation to each other; halfof the rolls being conveniently placed at one `elevation and alternaterolls at a lower elevation. Suitable guides 16 are associated with therolls 15 so that after the veneer has been directed by a suitable guide17 from the lowermost roll 3 to the first of the rolls 15, the guides 16will insure that the veneer will be properly guided past thc series ofrolls 15 by which it will be given a sinuous or wave-like configuration;but, being alternately waved in one direction and then the other as itpasses through the lower chamber sothat there will be no tendency tocause it to set permanently in curves or waves. After passing throughthe horizontal chamber, the veneer is wound on a roll B beyond the endof the chamber; this roll being preferably driven by a suitable drivingmechanism 18 which does not positively drive the roll of veneer butpermits slippage to occur; suchdrive mechanisms being commonly used 'inpaper making.

In the bottom of the chamber 14 are steam pipes 20 and the chamber isalso provided with fans 21, arranged at opposite ends of the rolls 15.The factors that determine the extent of drying of the veneer in thischamber are so regulated that the drying is carried to any`desired pointbe-lowthe fiber saturation point. The drying of the veneer in thehorizontal chamber is accompanied by a contraction or shrinking of theveneer transversely of the grain, that is in the di'- rection of travelof the sheet. It is for this reason that the rolls over which it passesin this chamber are spaced apart from each other, tlius avoiding thetearingof the material. The vveneer cannot vbe positively driven by therolls through the horizontal chamber as it is through the upright cham-lber but it is most conveniently pulled along from the end which is beingwound on the roll B. EvenV the slight pull required to draw the veneerthrough the horizontal chamber might cause the veneer to tear' andsplitting or cracking of the veneer in this chamber might also resultfrom other causes. In order to prevent the tearing of the veneer Neitherby the pull on the same while it is going through the horizontal chamberor from other causes, I apply to at least onev face of the veneer one ormorel tapes whichV are fed against the veneer when it reaches the bottomof the upright chamber, namely the point where a condition ofapproximate fiber saturation exists. Two such tapes, one along eachedge, are preferably applied. One of these tapes is shown in Fig. 2, thesame being wound on a roll C lying in front of a Slot 22 in the wall ofthe upright chamber at about the level of the top of the lowermost roll3. The tape o is carried from the roll C through an apparatus 23 forapplying glue or moisture, as the case may be. The tape is thencarriedvforward between the two lowermost rolls 3 and is pressed by the sameinto contact with the veneer; these two rolls serving also as the feedrolls for drawingv in the tape. i

As the taped veneer passes onward through the horizontal chamber, theveneer shrinks or contracts but the tape does not and, in order topermit the tape to serve its intended purpose it must be pressed downand the wrinkles therein flattened as wrinkles are formed during theshortening of the tape.- -This may conveniently be accomplished by.

so placedthat as the vencer passes between a roll 15 and thecorresponding pressure device, the members 25 and 2 6 engage the tapeand press it Hat, In this way, as the veneer shrinks, the tapes arealternately wrinkled and pressed so that they will serve elfectually tobind the veneer against splitting or crack- 1ng and will also givemechanical strength to the veneer to permit the same to be drawn throughthe lower chamber without danger of tearing the same. I f

I prefer to employ a higher temperature in the upright chamber than inthe lower chamber,- the temperature in the upright chamber beingpreferably somewhat. above the boiling point of water and thetemperature in the lower chamber being preferably below the boilingpoint of water.- The fans circulate the gaseous atmosphere within .the

lchambers, thus permitting rapid drying to beefected by reason of thepassage of currents of air across the surface of the veneer. Thehumidity lin each of the chambers may be controlled by varying thefamount of air that is drawn into the system in proportion to the amountof air and watery vapor that is (permitted to flow out through th'eflue, an by varying the pressure of the steam in the heating coils so astoxvary the temperature. Consequently the three factors.con

sisting of heat, humidity and convection may all beregulated so as toproduce rapid fir-ying Withoutinducing splitting or checki ing. y Itwill therefore be seenthat the veneer will be rapidly dried and, sinceit is bent first in one direction and then in the other as it travelsthrough the drying chambers, any tendency to Warp is entirely overcomeand when the veneer is dry and Wound up in the form of a roll as afinished product, all transverse lines will be straight, that iselements of the cylindrical shape Which the veneer takes when rolled up.

If desired, each ofthe rolls l5 may be provided with a shaft 27extending out through one side of the chamber 14 and provided with asquared end 28. A Wrench may be applied to the squared end of one shaftafter the other in the series of rollsin the horizontal chamber so as todraw the advanfing free end of a piece of veneer through the horizontalchamber and bring it in position to be engaged with the roll on which itis to be Wound up.

I claim:

1. The method of treating veneer which consists in drying it until themoisture content is in the vicinity of the fiber saturation point,applying adhesive tape to the veneer transversely of the grain, and thenfurther 'drying the veneer.

2. The method of treating veneer which consists in drying it until themoisture content is in the vicinity of the liber saturation point,applying adhesive tape to the veneer transversely of the grain, thenfurther drying the veneer, and pressing the tape against the veneer andiattening the same as wrinkles are produced in the tape by reason of theshrinking of the veneer.

3. The method of treating veneer which consists in partially drying itWhile bending it alternately in opposite directionsparallel to thefibres so as to maintain them straight` applying-adhesive tape to theveneer across the grain, and then further dryingthe veneer.

4. The method of treating veneer which consists in partially drying itwhile bending it alternately in opposite directions parallel to thefibres to maintain them straight, applying adhesive tape to the veneeracross the grain, further drying the veneer and at the same time bendingit alternately in opposite directions so as to malntain lines runningacross the same 1n the dlrection of the gram straight.

5. The method of treating veneer ivhich consists in partially drying itwhile bending it alternately in opposite directions paralle l to thelibres to keep them straight, applying-'adhesive tape to the veneeracross the grain, further drying the 4veneer and at the same timebending it alternately in opposite maining rolls of the series to befrictionallyl driven, and` passing heated air over the veneer While itis passing through the rolls.

7. The method of treating veneer which consists in applying adhesivetape to the veneer transversely of the grain and While the veneer stillcontains moisture to be re'- moved, and then 'drying the Veneer toremove such moisture.

8. The method of treating veneer which consists in drying it until themoisture content is in the vicinity of the fiber saturation point,cementing to the veneer a member to reinforce it transversely of thegrain, and then. further drying the veneer.

9.'Tl1e method of treating veneer which consists in drying it until themoisture content is in the vicinity of the fiber saturation point,applying adhesive tape to the veneer transversely of the grain along thetwo edges, and then further drying the veneer.

10. The method of drying veneer which consists in passing it over aseries of rolls arranged to cause the veneer to assume a sinuous shapealong lines transverse to the ibers in the veneer, While in contact withthe rolls and applying heat to the veneer during its passage over therolls.

11. The method of drying veneer which consists in bending it alternatelyin opposite directions parallel to the fibres to keep the ibresstraight, and simultaneously applyingheat to the veneer.

12. The method'of treating veneer which consists in drying it and,during the drying process, applying reinforcing strips to the surface ofthe veneer transversely of the grain. l y

13. The method of treating veneer which consists in drying it slowlyand, during .the

drying operation, gluing reinforcing strips i tion.

ARMIN ELMENDORF.

